Thurber, Jr. et al U.S. Pat. No. 6,575,386, entitled SPA NOZZLE WITH AIR ENTRAINMENT, issued Jun. 10, 2003, to the assignee hereof discloses a spa nozzle in which a jet of water passes over an air entrainment port downstream of the outlet. The present invention is an improvement over the Thurber, Jr. et al patent in that it relates to a small package size, oscillating fluidic for use in spa and bath products.
Increasing jet count and configurability of individual seats in hot tubs/spas and bath products are driving down the packaging envelope allowed for massage jets. These small packages are still required to have the same functionality as their larger brothers in terms of mechanical performance like shutoffs and massage performance, two key characteristics being water flow rate and airflow rate. The relatively high water flow rates and air flow rates are necessary and desirable to provide the necessary feel of the jet to provide a pleasurable, distinct massage. Use of fluidic jets, over spinners and the like, is highly desirable as they eliminate moving parts and reduce warranty costs. This type of jet is used in highly visible locations in the tub and needs to have good air for both physical feel and visual interest.
Previous fluidic spa jets have entrained air in two general locations: (1) the power nozzle region, or (2) the outlet region as disclosed in the above-mentioned Thurber, Jr. et al patent. Region 1 has the potential for entraining the most air, but the oscillator will stop working due to the large differences in the properties of air and water. Region 2 will oscillate and entrain air simultaneously. However, in the past the amount of air entrainment has been adequate for a spa application. The invention significantly improves on the latter, with the actual air-water interface on the sidewalls of the outlet region. The entrainment still occurs in the outlet region allowing stable oscillation with full air-water mixture. In fact, the quantity of air entrained relative to the quantity of water passing through the jet is more than twice any previous fluidic spa jet. In other words, the spa jet of the present invention is more than twice as effective in entraining air.
The spa nozzle disclosed herein has two distinct characteristics from previous fluidic spa nozzles: the first is the large aspect ratio, and the second is its dual air entrainment mechanism downstream of the throat.
Large aspect ratios offer a distinct packaging advantage because substantially more water flow rate can be delivered within the same circular cross-section. However, the resulting fluid mechanism have traditionally become more challenging, likely due to the formation of cross-flow patterns in the depth direction. The preferred aspect ratios (D/W) used in this nozzle are 3 (in a range of 2.9 to 3.1) at the power nozzle and 4.5 (in a range of 4.4 to 4.6) at the throat. We have found that in order for the fluidic to oscillate in a crisp, steady, and perceptible manner, the floor taper angle must not be greater than 5 degrees. In the early development stage, the nozzle had a 7 degree taper angle; its oscillation was erratic or the output jet rolled, which resulted in a muffled sensation to the end user. The taper angle was reduced to 5 degrees and later to 3 degrees. Substantial improvement was observed at both 5 and 3 degrees; but ultimately found 3 degrees to be preferred.
The dual air entrainment mechanism was developed to overcome previous mechanisms which did not provide sufficient air entrainment to satisfy or provide enhanced visual aspects. Although, in essence, the invention entrains air in a similar manner as to the previous method (by creating a low pressure region at the interface between the water jet and the air), the mechanism in this nozzle generates additional volume of air because it takes place in the plane of the oscillator as the water jet sweeps back and forth in the outlet structure. Additional volume results when the jet, due to its oscillatory nature, moves away from the air port at one of the sidewalls generating additional vacuum. A way to think about it is, low pressure is generated when there is a sudden expansion, the act of a jet rapidly moving away from the entrainment port has the effect of a sudden expansion, thus entraining additional amounts of air. Naturally, this effect is reproduced on the opposing wall and thus the presence of two air entrainment ports.
To satisfy the very constrained package space, a high aspect ratio (A-R=depth/width) is used for the fluidic circuit, 3 at the power nozzle and 4.5 at the throat is preferred. This high aspect ratio is necessary to achieve the preferred flow rate of the jet (4GPM@13PSI), and still fit in the allowable package space.
High aspect ratio jets have a tendency to produce unstable fluidic oscillators, where the cohesiveness of the stream or jet is lost. As illustrated in FIGS. 3A and 3B, this loss can be described as a stream of water that begins to skew and roll from the top of the stream to the bottom. As it rolls, the upper and lower layers of the stream begin to separate and oscillate out of phase to each other. The end result of this out-of-phase condition is that the massage effect is lost. The feel is so intuited that the user cannot determine the oscillation of the jet. The key to a good massage is the application of pressure and then the removal of said pressure. Jets that are moving out-of-phase to each other apply pressure to all contact areas all the time, as far as the nervous system of the body can tell. The relatively small contact patch on the user's body, due to proximity of the body to the jet, accentuates this problem.
As noted earlier, to prevent the rolling of the jet as it exits the nozzle, the floor taper angles are controlled as shown in FIG. 1B. Packaging requirements restricted the width of the interaction region, thus relatively large taper angles were needed to have the necessary throat area. However, if the angles exceeded the final design taper angles (about 3 degrees to no more than about 5 degrees), the jet rolled as it exited the nozzle.
Additionally, the tight packaging space required special manufacturing and assembly methods to be employed. The fluidic circuit geometry was split into three different components in the final assembly. As disclosed in Thurber, Jr., the fluidic circuit was packaged as a “wall-less” circuit to gain additional width normally consumed by the insert walls. The insert housing serves not only to hold the circuit, but acts as the outside walls of the feedback channels. The top of the communication port for the feedback channel forward to the throat was moved to a separate component.
The invention features a spa nozzle for use underwater having a water supply and an air supply, a fluidic oscillator for oscillating a jet of water back and forth, said fluidic oscillator having an interaction region and a pair of control ports at the upstream end of said interaction region and a power nozzle connected to said water supply for projecting a jet of water into said interaction region, a pair of feedback passages connecting said control ports with a downstream end of said interaction region, and said interaction region having an outlet aperture and a pair of diverging sidewalls extending downstream of said outlet aperture for issuing a sweeping jet of water into said spa, said power nozzle and said outlet aperture having a width W and a depth D, and said interaction region having sidewalls that diverge from said power nozzle and converge to said outlet aperture and a top and a bottom wall, the improvement wherein an air entrainment port is formed in each diverging side wall of said pair of diverging sidewalls downstream of said outlet aperture in alternating communication with said air supply as said jet of water is oscillated back and forth by said fluidic oscillator and provide enhanced air effects.
The invention further features a spa nozzle for use underwater, a water supply and an air supply, a fluidic oscillator for oscillating a jet of water back and forth, said fluidic oscillator having an interaction region and a pair of control ports at the upstream end of said interaction region and a power nozzle connected to said water supply for projecting a jet of water into said interaction region, a pair of feedback passages connecting said control ports with a downstream end of said interaction region, and said interaction region having an outlet aperture and a pair of diverging sidewalls extending downstream of said outlet aperture for issuing a sweeping jet of water into said spa, said power nozzle and said outlet aperture having a width W and a depth D, and said interaction region having sidewalls that diverge from said power nozzle and converge to said outlet aperture and a top and a bottom wall, the improvement wherein said top and bottom walls in said interaction region diverge sufficiently so as to provide a relatively large outlet aperture area but not so large as to cause said jet to roll as it exits said outlet aperture, e.g. no more than about 5 degrees and not less than about 3 degrees.
The invention further features a spa nozzle for use underwater, a water supply and an air supply, a fluidic oscillator for oscillating a jet of water back and forth, said fluidic oscillator having an interaction region and a pair of control ports at the upstream end of said interaction region and a power nozzle connected to said water supply for projecting a jet of water into said interaction region, a pair of feedback passages connecting said control ports with a downstream end of said interaction region, and said interaction region having an outlet aperture and a pair of diverging sidewalls extending downstream of said outlet aperture for issuing a sweeping jet of water into said spa, said power nozzle and said outlet aperture having a width W and a depth D, and said interaction region having sidewalls that diverge from said power nozzle and converge to said outlet aperture and a top and a bottom wall. The ratio of the depth D of said power nozzle to the width W thereof is from about 2.9 to about 3.1 and the ratio of the depth D of said outlet throat to the width W thereof is from about 4.4 to 4.6.
The invention further features a spa nozzle for use underwater, water supply and an air supply, a fluidic oscillator for oscillating a jet of water back and forth, said fluidic oscillator having an interaction region and a pair of control ports at the upstream end of said interaction region and a power nozzle connected to said water supply for projecting a jet of water into said interaction region, a pair of feedback passages connecting said control ports with a downstream end of said interaction region, and said interaction region having an outlet aperture and a pair of diverging sidewalls extending downstream of said outlet aperture for issuing a sweeping jet of water into said spa, said power nozzle and said outlet aperture having a width W and a depth D, and said interaction region having sidewalls that diverge from said power nozzle and converge to said outlet aperture and a top and a bottom wall. An air entrainment port is formed in each diverging side wall of said pair of diverging sidewalls downstream of said outlet aperture in alternating communication with said air supply as said jet of water is oscillated back and forth by said fluidic oscillator, and wherein said top and bottom walls in said interaction region diverge sufficiently so as to provide a relatively large outlet aperture area but not so large as to cause said jet to roll as it exits said outlet aperture, and wherein the ratio of the depth D of said power nozzle to the width W thereof is from about 2.9 to about 3.1 about and the ratio of the depth D of said outlet throat to the width W thereof is from about 4.4 to about 4.6.